fin rot or nibbling

Question
I have a bala shark that has been the last to adjust to a new aquarium.  I also have a dwarf puffer who I think has been nibbling the bala's fins. I have no proof because when I watch, I don't see the puffer getting close enough.  How can I tell the difference between fin rot, and nibbling?
Thank you for your help.

Answer
Hi Brandon;

I would suspect the puffer is nibbling. It's what they do. Puffers need to be in a tank with their own kind. They have teeth and will bite chunks out of other fish. Cute as a button, but oh so nasty!

You might need to know that bala sharks get 12 inches long. Very hyper, they can hurt themselves when they get startled in a tank too small. They are also schooling fish that should be in pairs or groups.

How long has your tank been set up?
Do you have other fish?

Followups Welcome

At Your Service;
Chris Robbins

Come on over and join us on the freshwater fish forum at About.com to get even more information too;
http://freshaquarium.about.com/od/questionsanswers/a/naavigateforum.htm

My member name is ChrisR62. See You There!